A Systematic Review of Epstein–Barr Virus Latent Membrane Protein 1 (LMP1) Gene Variants in Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is an aggressive tumor with a complex etiology. Although Epstein–Barr virus (EBV) infection is known environmental factor for NPC development, the degree to which EBV naturally infects nasopharyngeal epithelium and the moment when and why the virus actively begins to affect cell transformation remains questionable. The aim of this study was to explore the association between LMP1 gene variability and potential contribution to NPC development. A systematic review was performed through searches of PubMed, Web of Science (WoS) and SCOPUS electronic databases. Additionally, meta-analysis of the difference in the frequency of seven LMP1 gene variants in NPC and control individuals was accomplished. The results from this study give a proof of concept for the association between 30 bp deletion (OR = 3.53, 95% CI = 1.48–8.43) and Xhol loss (OR = 14.17, 95% CI = 4.99–40.20) and NPC susceptibility when comparing biopsies from NPC and healthy individuals. Otherwise, 30 bp deletion from NPC biopsies could not distinguish NPC from EBV-associated non-NPC tumors (OR = 1.74, 95% CI = 0.81–3.75). However, B95-8, China1 and North Carolina variants were uncommon for NPC individuals. Much more efforts remains to be done to verify the biological significance of the differences observed, define so-called “high-risk” EBV variants and make it available for clinical application.

FOXA1 Expression in Nasopharyngeal Carcinoma: Association with Clinicopathological Characteristics and EMT Markers

The forkhead box (FOXA) family of transcription factors regulates gene expression and chromatin structure during tumorigenesis and embryonic development. Until now, the relationship between FOXA1 and the nasopharyngeal carcinoma (NPC) has not yet been reported. Therefore, our purpose is to analyze the expression of FOXA1 in 56 NPC patients compared to 10 normal nasopharyngeal mucosae and to correlate the expression with the clinicopathological features. Besides, we investigated the association between FOXA1 and LMP1 gene expression, as well as the EMT markers namely the E-cadherin and Twist1. Among 56 NPC tissues, 34 (60.7%) cases were positive for FOXA1. Furthermore, we noticed that FOXA1 expression correlated with TNM (p=0.037), and age at diagnosis (p=0.05). Moreover, positive expression of FOXA1 is likely to be associated with prolonged disease-free survival and overall survival rates. On the other hand, we observed a positive association between the expression of E-cadherin and FOXA1 (p=0.0051) whereas Twist1 correlated negatively with FOXA1 (p=0.004). Furthermore, knowing that LMP1 plays a key role in the pathogenesis of NPC, we explored the association of FOXA1 with the LMP1 gene expression in both NPC cell lines and tissues. We found that, in the C666-1 which displays low levels of LMP1, the expression of FOXA1 is high, and inversely in the C15 cell line that expresses a high level of LMP1, the level of FOXA1 is low. Besides, in accordance to our results, we found that in NPC tissues there is a negative association between LMP1 and FOXA1. In conclusion, our results suggest that the overexpression of FOXA1 is associated with a nonaggressive behavior and favorable prognosis in NPC patients. FOXA1 could contribute in the EMT process through key factors as E-cadherin, Twist1, and LMP1.

LMP1 gene detection using a capped gold nanowire array surface plasmon resonance sensor in a microfluidic chip

A new detection device by using SPR nanowire array chip and a microfluidics system was developed. A simple, low-cost and reproducible SPR nanowire chip with a visible light source displayed real-time detection capability.

Integrated analysis of the miRNA-mRNA network associated with LMP1 gene in nasopharyngeal carcinoma

Epstein-Barr virus oncogenic latent membrane protein 1 (LMP1) has been known to play important roles in nasopharyngeal carcinoma (NPC). LMP1 gene also induced a variety of microRNAs (miRNAs) which bear pivotal roles in regulation of mRNAs expression. However, little was known about the global change of mRNAs and miRNAs induced by LMP1 gene in NPC. In our study, one NPC tissue microarray profile and two LMP1-associated microarray expression profiles data were downloaded from the Gene Expression Omnibus database. A protein-protein interaction network was constructed by using bioinformatics platform Gene-Cloud of Biotechnology Information (GCBI). 78 differentially expressed miRNAs and 3322 differentially expressed genes were identified in order to generate a macroscopic network between miRNAs and mRNAs associated with LMP1 gene. In addition, two significant models were generated to illustrate the expression tendency. Our study provided a way to reveal the interaction between miRNAs and mRNAs in LMP1 axis, bringing insights into the pathogenesis of NPC.

Activity of the LMP1 gene promoter in Epstein–Barr virus-transformed cell lines is modulated by sequence variations in the promoter-proximal CRE site

The Epstein–Barr virus (EBV)-encoded tumour-associated latent membrane protein 1 (LMP1) gene expression is transactivated by EBV nuclear antigen 2 (EBNA2) in human B cells. We have previously identified a cyclic AMP-responsive element (CRE) in the B95-8 LMP1 promoter that is essential for transcription activation. Sequencing of LMP1 promoter in the P3HR1-derived EREB2.5 cell line revealed 25 single base pair substitutions in comparison to the B95-8 virus, one of them localized in the CRE element. Sequence variations in this element have been identified in several EBV isolates of both African and Asian origins. The effect of the P3HR1 CRE site variation on binding of factors to the LMP1 promoter sequence (LRS) and promoter activation was investigated with electrophoretic mobility-shift assays and reporter gene transfection assays. ATF1 and CREB1 transcription factors bound with reduced efficiency to the P3HR1 variant and below the detection level to the other tested variants. Accordingly, reporter plasmids carrying the P3HR1 CRE sequence in a B95-8 LRS context displayed 50 % lower activity in all tested cell lines. The impaired ability to activate transcription caused by the C to A substitution in CRE was not apparent when the mutated site was placed in a P3HR1 LRS context and the reporter transfected into Jijoye cells, most likely as a consequence of the other base pair substitutions in P3HR1 LRS. Overall, our results suggest that the mutations in the LRS CRE site have been conserved to adjust LMP1 expression to levels that favour cell survival in certain cellular and environmental contexts.